Valve for controlling pressure and flow

A fluid dispenser for dispensing a liquid in an intermittent manner including a recirculation loop for circulating said liquid when said dispenser is off and a variable restrictor valve in said recirculation loop for adjusting the pressure therein, the fluid dispenser comprising:

• a first cylindrical chamber communicating with a fluid outlet,
• a second cylindrical chamber having a fluid inlet communicating therewith and being larger in diameter than said first chamber,
• an axially adjustable elongated cylindrical valve member contained with a sliding fit within said first chamber and including a helical groove in an outer surface portion thereof, said valve member having and outer surface in abutting relationship to a wall of said first chamber to create a restricted flow path within said helical groove, said groove communicating with said first chamber and said fluid outlet at a downstream end and with said second chamber and said fluid inlet at an upstream end,
• a seal assembly coupled to said valve member and disposed in said second chamber for movement with said valve member and creating a dynamic seal with an inner wall of said chamber, and
• a sleeve and a valve stem attached to said valve member wherein said sleeve and said valve stem have respectively mating internal and external threaded portions, and said valve stem being received by said sleeve whereby rotation of said valve stem causes axial adjustment of said valve stem with respect to said sleeve and adjustment of the amount of said helical groove contained within said first chamber and said external threaded portion on said valve stem being of smaller diameter than said seal assembly and said second chamber.